Persistent low mash pH

Sun Mar 13, 2016 6:04 am

You always hear about lowering the pH, acidifying the water, etc. However, I have the opposite problem where my mash pH is always low. I use the ColorpHast strips and I alway end up around 4.8 or so when I dough in, even when doing an all pilsner grist and adding a couple grams of chalk (which I have decided does almost nothing).

I usually end up adding 2-4g of baking soda to get the pH up to where it needs to be. The water I'm using is pretty soft (see below) so I would think that I would end up just about where I wanted if I used that and a pale grist. The readings blow are from 3 measurements of the city's water:

Ca : 5-6
Mg : 1
Na : 40-45
Cl : 40-50
SO4: 15 - 18
CaCO3: 30 - 38
pH: 6.75-7.7

Anyone have any better suggestions on how to raise the pH other than chalk and baking soda? I don't want to put all that sodium in, but the chalk doesn't seem to do anything (I added 5g and it didn't shift notably over 10 minutes).

Thanks
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Re: Persistent low mash pH

Sun Mar 13, 2016 6:12 am

NateBrews wrote:You always hear about lowering the pH, acidifying the water, etc. However, I have the opposite problem where my mash pH is always low. I use the ColorpHast strips and I alway end up around 4.8 or so when I dough in, even when doing an all pilsner grist and adding a couple grams of chalk (which I have decided does almost nothing).

I usually end up adding 2-4g of baking soda to get the pH up to where it needs to be. The water I'm using is pretty soft (see below) so I would think that I would end up just about where I wanted if I used that and a pale grist. The readings blow are from 3 measurements of the city's water:

Ca : 5-6
Mg : 1
Na : 40-45
Cl : 40-50
SO4: 15 - 18
CaCO3: 30 - 38
pH: 6.75-7.7

Anyone have any better suggestions on how to raise the pH other than chalk and baking soda? I don't want to put all that sodium in, but the chalk doesn't seem to do anything (I added 5g and it didn't shift notably over 10 minutes).

Thanks

From what I've read chalk doesn't mix very well with water and it gets worse with temperature. Maybe add it in while the mash water is still cold. Or hold the dark grains out until vorlof.
Last edited by NervousDad on Sun Mar 13, 2016 6:28 am, edited 1 time in total.
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Re: Persistent low mash pH

Sun Mar 13, 2016 6:27 am

I have tried some experiments with what the level of dark grains are in the grist to see if that was the culprit. It turns out that even if I make a little test mash with 100% weyermann pilsner malt, I still get a pH that is about 5.

I am making a black mild now with most of the dark grains held back, and with 5g of chalk and 2g of baking soda, the mash came in at 4.9. I added 3g more baking soda and now it is up to 5.2 or so.
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Re: Persistent low mash pH

Sun Mar 13, 2016 7:28 am

NateBrews wrote:I have tried some experiments with what the level of dark grains are in the grist to see if that was the culprit. It turns out that even if I make a little test mash with 100% weyermann pilsner malt, I still get a pH that is about 5.

I am making a black mild now with most of the dark grains held back, and with 5g of chalk and 2g of baking soda, the mash came in at 4.9. I added 3g more baking soda and now it is up to 5.2 or so.


How are you measuring that pH? There is absolutely no way that 100% Pils malt in distilled water at our typical water/grist ratios is going to produce a pH that low. The typical distilled water pH for that really pale base malt is 5.7 to 5.8. There have been cases where a maltster creates a more acid batch, but its not typical. Even then, the pH probably won't go below about 5.4.

Remember, the ONLY accurate pH measurement is made with a freshly calibrated pH meter on a room-temperature wort sample. Strips are useless in brewing...the plastic strips can be somewhat useful though.
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Re: Persistent low mash pH

Sun Mar 13, 2016 7:42 am

This was measured using the ColorpHast brand strips (the only ones that are useful at all). They are the ones that Jamil says to use and Kai Troester did a study on. In his tests, they were consistently 0.3 points low, but this was a systemic offset that, so long as you know it, isn't an issue.

So, the sample method is to take a spoon full of the mash and chill it on an ice pack (I just hold the back of the spoon on a gel ice pack that conforms to the spoon) and once cool I dip the strip in for the specified time and then judge against the color chart under a daylight bulb.

To the uselessness of strips, I have used the cheap strips before and they are total junk. The ColorpHast ones seem to be much better (they should given that they are 10x the price).
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Re: Persistent low mash pH

Sun Mar 13, 2016 8:02 am

Ok, since conjecture and dogma aren't the way to do things I performed an experiment.

I have a tub of Five Star 5.2 stabilizer (I don't use it anymore, but I still have it from when I did), so I took 37mL of RO water and added 0.03g of stabilizer to it then heated it in the microwave to 150F. Then I took a clean spoon, and put a sample in the spoon and chilled on the same ice pack as before and measured the temperature of the sample at 84F (a bit high, but not too bad).

I took the other piece of the same strip (I cut them in 3) and measured that sample and it showed the sample to have a pH between 5 and 5.3.

So if the stabilizer is made to give a 5.2 pH at 150F and you get a +0.3 offset due to being at room temp instead of mash temp, and then the strips give a -0.3 offset then I should measure 5.2 with the strip. Given that the result of the experiment was between 5 and 5.3 (that is the scale on the package), I think the strips are showing roughly the right thing.
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Re: Persistent low mash pH

Mon Mar 14, 2016 9:00 am

How is the beer turning out?
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Re: Persistent low mash pH

Mon Mar 14, 2016 9:28 am

The beer is turning out OK. I'm not 100% happy with it. In comps it has been scoring mid 30s with a couple low 40s outliers. I have gotten a couple notes back on black beers (mild, porter) that said there was some astringency and/or sharpness to them. My pilsners never seem quite right to me and I have been generally blaming fermentation, but I'm curious if my pH is messed up in the mash and that is rippling through the rest of the process.

My amber color beers are the ones that score the highest and I'm the happiest with, which I think would be in line with them being the most tolerant to the water chemistry being a bit off.
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